++++++++++++++++++++ See also Building Tools ++++++++++++++++++++ From: "Don Brown" To: "Elecraft" Subject: Re: [Elecraft] It can be done! - Bench equipment Date: Wed, 10 Apr 2002 12:06:46 -0500 Hi All Here are some thoughts I have on bench equipment. The minimum requirement= is a DVM, a power supply, a soldering iron/station and some hand tools. = you may need more than one power supply. One medium to high current (say = 5 - 25 amps) to power 12 volt stuff like radios. A fused car battery or h= am type power supply could handle this. An adjustable supply with a curr= ent limit for experimenting is also nice to have (say 0-25 volts at 1 or = 2 amps). If the DVM doesn't have current ranges get a .1 ohm and .01 ohm = 5 or 10 watt 1% resistor to use as a shunts for your meter. Even if your = meter has a current range its is safer to use the shunt resistors. If you= make a mistake in current measuring you will blow the meter fuse or the = internal meter shunt. With the resistor just put in series with the circu= it and measure the voltage drop. The .1 reads 1 amp at 100 mV and the .01= reads 10 amp at 100 mV easy math. One of the handiest and simplest additions I made to my bench many years = ago is a 3/4" x 1/2" deep trough along the edge of the work bench. I moun= ted a 2x4 flush with the front edge of the bench and used a router to cut= the trough. This trough catches any small parts before they can fall off= on the floor and you can sweep lead clippings from the bench into the tr= ough and then into the trash can off the end of the bench. A good lamp, chair and magnifier is also needed. I use a 7 power hastings= hand magnifier from Edmond Scientific but that's just my preference. You= may find something else works better. There are a lot of scopes out there new and used. I think I would look at= some of the Tektronix or HP used analog scopes and would go for 100 MHz = or better. There are some real bargains. Just be sure the CRT is good. Th= e way to tell is to check for double peaking. Turn down the intensity the= n watch as you increase the intensity. If the intensity increases then di= ms as you turn up the control then the CRT is not up to snuff. It may sti= ll have some life left, just be cautious, and the price should reflect th= is. Also check the attenuators. Connect to the calibrator wiggle the V/Di= v knob and make sure the trace is steady and the amplitude reduces proper= ly as you change ranges then check the time base knob the same way. Then = connect the input to a sine wave and adjust the V/Div for several divisio= ns of amplitude centered. Adjust the trigger in normal mode so the start = of the sine wave just crosses the center of the screen. Switch from plus = to minus trigger and the start of the sine wave should cross the center l= ine at the same point just in the reverse direction. Reduce the amplitude= down to .2 divisions you should still be able to trigger on the sine wav= e. At this point you have a well equipped bench and most other stuff is just= nice to have if you can afford and justify it. Generators are easy to bu= ild or use your transmitter. There are frequency counter kits, Watt meter= kits and function generator kits at low cost. You don't have to spend a lot of money to have fun although you can spend= a lot if you can and want. Same as with almost any hobby. Don Brown KD5NDB ----- Original Message ----- From: Tim and Nancy Logan Sent: Wednesday, April 10, 2002 9:35 AM To: Elecraft Cc: tentec reflector; QRP-l; George, W5YR; Bill Golden Subject: [Elecraft] It can be done! Hi folks - I received a lot of replies from good folks when I went shopping for an oscillscope on a small budget. I wanted to let all know that I received my Tektronics 465M today via Ebay which I paid about $130 for. An engineering friend helped me check it out and it works perfectly. So I just wanted you budding experimenters on a low budget to know that it can be done. A function generator is now on the way from a VERY reliable ebay source - it ran about $175 and can take care of most needs. Just thought I would share this with those who might be interested. 73/Tim Logan NZ7C ++++++++++++++++++